1. Field of the Invention
The present invention pertains to well tools and methods of use therefor. In particular, the present invention pertains to a tool for cleaning out, reshaping or reaming well conduits, or for making new hole in a well or for other uses. Specifically, the present invention pertains to well tools and methods for use thereof which are especially designed for use with continuous coiled pipe operations but which may advantageously be used with any suitable fluid supply line, including conventional jointed tubing. As used herein, the term "fluid" is intended to include both liquid and gas.
2. Background of the Prior Art
Drilling a well requires expensive equipment and operation. Usually the drill string comprises joints of pipe which are connected together as drilling progresses. A derrick is required for handling such pipe. In the past, it has been necessary, in changing a bit or in other operations, to pull the drill string, disconnecting and stacking joints of pipe. This also requires, in addition to the derrick, a considerable amount of time.
In the past, even working over a non-productive or malfunctioning well has required equipment capable of pulling strings of pipe and disconnecting the joints thereof. To eliminate derricks and associated equipment, some workover or remedial operations have been handled by running various tools into the well on a cable. However, cable workover methods have several limitations, including the inability to utilize fluid flow in the remedial operations.
In recent years, continuous pipe or tubing units have been developed to eliminate some of the problems of conventional workover operations. In the continuous tubing units, a continuous string of small diameter pipe or tubing is coiled on a reel device and the continuous pipe is fed through an injector device which straightens the tubing and feeds it from the reel down into the well. Such an operation eliminates the need for a derrick and for the time-consuming operation of connecting joints of pipe together. Coiled tubing units are described in U.S. Pat. Nos. 3,116,793; 3,313,346; and 3,346,045.
Coiled tubing units may be used for several types of workover operations. For example, wells having sand bridges or which are filled with sand from top to bottom may be cleaned by injecting the continuous pipe into the well while circulating fluids therethrough. Coiled tubing units are often used to "kick wells off," in place of gas lifting or swabbing, by injecting nitrogen or natural gas into the well or by replacing workover fluid with diesel or lease crude. Production zones may be acidized, inhibited, sand-consolidated, gravel packed, squeezed off or partially plugged back to shut off bottom water using coiled tubing units. Foreign matter in the tubing, such as paraffin, may be removed by circulation of hot oil or solvent through continuous coiled tubing units. It will be appreciated that such units are highly flexible in workover operations.
However, there may be situations where circulation of a fluid through a coiled tubing unit will not remedy the problems of a potentially productive well. For example, the well tubing may become plugged with inoperative equipment or foreign matter which cannot be dissolved or washed out by circulation of fluids. In other cases, the production tubing itself may be corroded, deformed or otherwise defective.